How can I render a model with both alpha textures and backface culling?
Try this arrangement for your model. The way you have it setup in your image, you're mixing white with your image using alpha as a factor. If you want transparency, you will have better luck with this arrangement. Pay attention to the right side where I highlighted the blend modes - these are necessary for transparency. Pick Alpha-Clip, Alpha-Hashed, or Alpha-Blend (whatever looks best), just not Opaque. This should be applied to the Shadow Mode as well - depending on what type of shadows you want for your transparency.

Hope this helps